Telescope sights or riflescopes are used by shooters to enable accurate aiming of firearms such as rifles, pistols, shotguns and the like. These optical sights are typically mounted in an elongated tubular barrel or housing carrying conventional ocular and objective lens systems. An erector-lens system is provided between the ocular and objective systems to provide an erect target image for viewing by the shooter.
A conventional riflescope includes a reticle, typically of cross hair or post form, which is seen by the shooter in silhouette and superimposed over the target image. The position of the firearm is adjusted until the reticle is positioned on a target-image aiming point.
In using the scope to its fullest extent, a user must properly adjust for several external factors. A factor which must be taken into account in long-range shooting is the curved trajectory traversed by a bullet as it falls below the axis of the rifle bore while traveling the distance from the rifle muzzle to the target, i.e., “range.” Other common factors include wind condition and ballistic coefficient. Typically, such adjustments are approximated by means of the reticle. Thus, reticles which enable a shooter to quickly and accurately make such field adjustments are particularly advantageous.